John M Betts

Monash University (Australia) · Faculty of Information Technology

A common problem in pixelwise classification or semantic segmentation is class imbalance, which tends to reduce the classification accuracy of minority-class regions. An effective way to address this is to tune the loss function, particularly when Cross Entropy (CE), is used for classification. Although several CE variants have been reported in pre...

The role of online communities of the extreme-right in the radicalization of individuals involved in political violence has received increased public attention due to recent tragic events around the world. In this policy brief, we provide a systematic account of the psychological processes underpinning the formation and transformation of these comm...

In recent years, the reach and influence of far-right ideologies have been extended through online communities with devastating effects in the real world. In this research, we examine how far-right online communities can be empowered by socio-political events that are significant to them. Using over 14 years of data extracted from an Australian nat...

In this work we consider an information-based system to reduce metropolitan rail congestion in Melbourne, Australia. Existing approaches aim to reduce congestion by asking commuters to travel outside of peak times. We propose an alternative approach where congestion is reduced by enabling commuters to make an informed trade-off between travel time...

In this paper, we propose a Dual Focal Loss (DFL) function, as a replacement for the standard cross entropy (CE) function to achieve a better treatment of the unbalanced classes in a dataset. Our DFL method is an improvement on the recently reported Focal Loss (FL) cross-entropy function, which proposes a scaling method that puts more weight on the...

In this work we consider an information-based system to reduce metropolitan rail congestion in Melbourne, Australia. Existing approaches aim to reduce congestion by asking commuters to travel outside of peak times. We propose an alternative approach where congestion is reduced by enabling commuters to make an informed trade-off between travel time...

Medical imaging based prostate cancer diagnosis procedure uses intra-operative transrectal ultrasound (TRUS) imaging to visualize the prostate shape and location to collect tissue samples. Correct tissue sampling from prostate requires accurate prostate segmentation in TRUS images. To achieve this, this study uses a novel residual connection based...

Despite the increasing citizen engagement with socio-political online communities, little is known about how such communities are affected by significant offline events. Thus, we investigate here the ways in which the collective identity of a far-right online community is affected by offline intergroup conflict. We examine over 14 years of online c...

The role of online communities in shaping behaviours ‘in real life’ (IRL) is well-established, however, less is known about how such communities are affected by offline events. Thus, we investigate here the ways in which the collective identity of a far-right online community is affected by offline intergroup conflict. That is, we examine over 14 y...

A number of clinical trials are investigating the role of prostate focal brachytherapy as an alternative treatment to whole gland therapy, offering the opportunity for tumour dose escalation and/or reduced toxicity. Brachytherapy, either low dose rate or high dose rate, offers a treatment choice with both precision in dose delivery and opportunity...

Renewable energy production is increasing, and the cost of power storage is decreasing, enabling users to exercise control over their power consumption from the electricity grid. To achieve partial or complete energy independence, consumers need to be able to calculate the energy storage required to cover periods when renewable power is not being p...

Low-risk prostate cancer can be treated by focal brachytherapy, in which small radioactive seeds are implanted directly into the prostate at targeted locactions. Treatment planning is complicated by post-operative displacement of the seeds from their intended location. This reduces the actual dose received by the prostate and increases the dose to...

Focal brachytherapy is a clinical procedure that can be used to treat low-risk prostate cancer with reduced side-effects compared to conventional brachytherapy. Current practice is to man- ually plan the placement of radioactive seeds inside the prostate to achieve a desired treatment dose. Problems with the current practice are that the manual pla...

Treatment plans for ten patients, initially treated with a conventional approach to low dose-rate brachytherapy (LDR, 145 Gy to entire prostate), were compared with plans for the same patients created with an inverse-optimisation planning process utilising a biologically-based objective. The 'biological optimisation' considered a non-uniform distri...

A hybrid simulation model is developed to determine the cost-minimizing target level for a single-item, single-stage production-inventory system. The model is based on a single discrete-event simulation of the unconstrained production system, from which an analytical approximation of the inventory shortfall is derived. Using this analytical express...

The cost of monitoring and updating the location of Moving Queries is very high, as the calculation of a range query needs to be re-evaluated whenever the query moves. Previous efforts to reduce this cost have proposed reducing the frequency of communication between query and server. However, because all possible objects continue to be surveyed usi...

An accurate model for the inventory shortfall distribution is necessary to calculate the target level required to give a desired service level in manufacturing systems under stochastic demand and production capacity constraint. Existing methods for modelling the inventory shortfall require that the demand distribution be expressible in functional f...

With mobile moving range queries, there is a need to recalculate the relevant surrounding objects of interest whenever the query moves. Therefore, monitoring the moving query is very costly. The safe region is one method that has been proposed to minimise the communication and computation cost of continuously monitoring a moving range query. Inside...

As the number of mobile devices is experiencing an explosive growth, mobile query processing has become an important application of mobile devices. One of the most frequently used mobile queries is range queries - retrieving surrounding objects of interest. As mobile devices are moving, these range queries are literally moving range queries. The ma...

The cost of monitoring and keeping the location of a Moving Query updated is very high, as the calculation of the range query needs to be re-evaluated whenever the query moves. Many methods have been proposed to minimize the computation and communication costs for the continuous monitoring of Moving Range Queries. However, because this problem has...

A model is developed to calculate the inventory target level required to provide a specified service level in a single-item single-stage inventory when production is subject to a capacity constraint. The model provides a reliable alternative when the exact Markov chain method is intractable, and where known approximations become unreliable due to h...

This paper attempts to answer the question of how much of its current production a gold producer should hedge by forward selling. We develop a model which allows a company manager to determine the optimal (profit-maximising) hedge, and an estimate of the risk of company failure, based on an estimate of the forward price of gold; the mine's operatin...

When purchased components for an assembly manufacturing operation are replenished Just-In-Time the investment in inventory holding of these components is eliminated, but usually with increased fixed reorder cost. It is therefore important in the pursuit of high returns on inventory investment to know for which components JIT replenishment is an opt...

The predominant approach to determining replenishment batch sizes for capital constrained multi-item inventories is to assume that at some point in time the replenishment of all items will coincide, and that batch sizes are small enough that the constraint is not violated when this event occurs. However, when an inventory consists of a large number...

While just-in-time ideas have been enthusiastically embraced by manufacturing practitioners, the small replenishment batch sizes advocated are difficult to reconcile with the standard management science cost trade-off approach. In a previous paper by the authors, which analysed a multi-product manufacturing scenario under deterministic demand, this...

New start-up companies, which are considered to be a vital ingredient in a successful economy, have a different objective than established companies: They want to maximise their chance of long-term survival. We examine the implications for their operating decisions of this different criterion by considering an abstraction of the inventory problem f...

Efficient Consumer Response (ECR) is designed to make the grocery industry more efficient. Although it originated in the US, the concept has been adopted in many regions. To enrich the findings of the existing studies that indicate a slow diffusion rate of ECR, this study examines ECR adoption in Australia by conducting a survey. The findings sugge...

While JIT ideas have been enthusiastically embraced by manufacturing practitioners, the small replenishment batch sizes advocated are difficult to reconcile with the standard management science cost trade-off approach. The difficulty is diagnosed as being due to the standard assumption that capital for inventory is borrowed and hence boundless. We...

A simulation study of an idealised world of agents trading a single generic product is presented. The population consists of agents using forward planning and agents reacting to the current situation who are in direct interaction and competition. The object of the simulation is to study the relative efficacy of planning and reactive policies for ag...